Java中的 BigInteger intValueExact() 方法及示例

Java.math.BigInteger.intValueExact()是在Java 8 中引入的。它是一个内置函数，可以将 BigInteger 的值转换为 int 并检查丢失的信息。如果 BigInteger 的值大于 2,147,483,647 或小于 -2,147,483,648；该方法将抛出ArithmeticException ，因为 BigInteger 不适合 int 范围。

句法：

public int intValueExact()

返回值：此方法返回此 BigInteger 的 int 值。

异常：如果 BigInteger 的值大于 2,147,483,647 或小于 -2,147,483,648，则该方法抛出ArithmeticException ；因为这个范围不适合 int 范围。

例子：

Input: 4561561
Output: 4561561
Explanation: 4561561 is given as input which is bigInteger
and int value of 4561561 is 4561561

Input: -8546512
Output: -8546512
Explanation: -8546512 is given as input which is bigInteger 
and int value of -8546512 is -8546512

Input: 3000000000
Output: ArithmeticException
Explanation: When 3000000000 is tried to convert to int,
since 3000000000 > 2,147,483,647 (greater than a int's range), 
therefore it throws an arithmetic exception.

下面的程序说明了 BigInteger 类的 intValueExact() 方法：

程序 1：演示正数 <2,147,483,647 的 intValueExact() 方法

// Java program to demonstrate intValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // Creating a BigInteger object
        BigInteger big;
        big = new BigInteger("4561561");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        // convert big to the int value
        int b1 = big.intValueExact();
  
        // print int value
        System.out.println("int converted value : "
                           + b1);
    }
}

输出：

BigInteger value : 4561561
int converted value : 4561561

程序 2：演示负数 >-2,147,483,648 的 intValueExact() 方法

// Java program to demonstrate intValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("-8546512");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        // convert big to the int value
        int b1 = big.intValueExact();
  
        // print int value
        System.out.println("int converted value : "
                           + b1);
    }
}

输出：

BigInteger value : -8546512
int converted value : -8546512

程序 3：演示负数 <-2,147,483,648 的 intValueExact() 方法。它会抛出算术异常

// Java program to demonstrate intValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("-3000000000");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        try {
            // convert big to the int value
            int b1 = big.intValueExact();
  
            // print int value
            System.out.println("int converted value : "
                               + b1);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

BigInteger value : -3000000000
Exception: java.lang.ArithmeticException: BigInteger out of int range

程序 4：演示正数 >2,147,483,647 的 intValueExact() 方法。它会抛出算术异常

// Java program to demonstrate intValueExact()
// method of BigInteger Class
  
import java.math.*;
  
public class GFG {
  
    public static void main(String[] args)
    {
  
        // Creating a BigInteger object
        BigInteger big = new BigInteger("3000000000");
  
        // print value of BigInteger
        System.out.println("BigInteger value : "
                           + big);
  
        try {
            // convert big to the int value
            int b1 = big.intValueExact();
  
            // print int value
            System.out.println("int converted value : "
                               + b1);
        }
        catch (Exception e) {
            System.out.println("Exception: " + e);
        }
    }
}

输出：

BigInteger value : 3000000000
Exception: java.lang.ArithmeticException: BigInteger out of int range

参考： https: Java